Checks and balances, principle of government under which separate branches are empowered to prevent actions by other branches and are induced to share power. Checks and balances are applied primarily in constitutional governments. They are of fundamental importance in tripartite governments, such as that of the United States, which separate powers among legislative, executive, and judicial branches.

The Greek historian Polybius analyzed the ancient Roman mixed constitution under three main divisions: monarchy (represented by the consul); aristocracy (the Senate); and democracy (the people). He greatly influenced later ideas about the separation of powers.

Checks and balances, which modify the separation of powers, may operate under parliamentary systems through exercise of a parliament’sprerogative to adopt a no-confidence vote in a government; the government, or cabinet, in turn, ordinarily may dissolve the parliament. The British Parliament is supreme, and laws passed by it are not subject to review by the courts for constitutionality. In France, under the Fifth Republic (1958), a Constitutional Council of nine members (appointed for nine years by the president, Senate, and National Assembly) reviews the constitutionality of legislation. The Federal Republic of Germany combines features of parliamentary systems and of federal systems like that of the United States. It vests the right to declare a law unconstitutional in the Federal Constitutional Court (1951).

The framers of the U.S. Constitution, who were influenced by Montesquieu and William Blackstone among others, saw checks and balances as essential for the security of liberty under the Constitution: “It is by balancing each of these powers against the other two, that the efforts in human nature toward tyranny can alone be checked and restrained, and any degree of freedom preserved in the constitution” (John Adams). Though not expressly covered in the text of the Constitution, judicial review—the power of the courts to examine the actions of the legislative and the executive and administrative arms of government to ensure that they are constitutional—became an important part of government in the United States. Other checks and balances include the presidential veto of legislation (which Congress may override by a two-thirds vote) and executive and judicial impeachment by Congress. Only Congress can appropriate funds, and each house serves as a check on possible abuses of power or unwise action by the other. Congress, by initiating constitutional amendments, can in practice reverse decisions of the Supreme Court. The president appoints the members of the Supreme Court but only with the consent of the Senate, which also approves certain other executive appointments. The Senate also must approve treaties.

John Adams, oil painting by Gilbert Stuart, 1826; in the National Collection of Fine Arts, …

Courtesy of the Smithsonian American Art Museum (formerly National Museum of American Art), Washington, D.C.

From 1932 the U.S. Congress exercised a so-called legislative veto. Clauses in certain laws qualified the authority of the executive branch to act by making specified acts subject to disapproval by the majority vote of one or both houses. In 1983, in a case concerning the deportation of an alien, the U.S. Supreme Court held that legislative vetoes were unconstitutional (the House of Representatives had overturned the Justice Department’s suspension of the alien’s deportation). The decision affected clauses in some 200 laws covering a wide range of subjects, including presidential war powers, foreign aid and arms sales, environmental protection, consumer interests, and others. Despite the court’s decision, Congress continued to exercise this power, including the legislative veto in at least 11 of the bills it passed in 1984 alone.

Checks and balances that evolved from custom and Constitutional conventions include the congressional committee system and investigative powers, the role of political parties, and presidential influence in initiating legislation.

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